[DISC] Add runtime configuration for OpenHAB (#1658)

* [DISC] Add runtime configuration for OpenHAB

Add an MQTT configurable system key "ohdiscovery" for OpenHAB auto discovery

* Docs and environments update

platformio.ini

@@ -41,7 +41,6 @@ extra_configs =
 ;default_envs = esp32dev-gf-sun-inverter
 ;default_envs = esp32dev-ir
 ;default_envs = esp32dev-ble
-;default_envs = esp32dev-ble-openhab
 ;default_envs = esp32dev-ble-mqtt-undecoded
 ;default_envs = esp32dev-ble-aws
 ;default_envs = esp32feather-ble
@@ -82,7 +81,6 @@ extra_configs =
 ;default_envs = nodemcuv2-rf-cc1101
 ;default_envs = nodemcuv2-somfy-cc1101
 ;default_envs = manual-wifi-test
-;default_envs = openhab-test
 ;default_envs = nodemcuv2-mqtt-fw-test
 ;default_envs = rf-wifi-gateway
 ;default_envs = nodemcuv2-rf2